I have a used G17 Gen3 with the ghost trigger and spring installed... today I experienced some double taps when shooting... I'm new to shooting handguns and was wondering if anyone has an easy check on parts to determine why I had double taps...

I'm not sure how many rounds went through this gun since its a used gun that came with a NY trigger which I had changed out to the ghost rocket and lighter trigger spring....

what I do notice is that when I hold the trigger depressed, point the gun up and slowly releasing the slide its not smooth. it seems like it snags and then slides then snags again towards the end.

could this be a worn recoil spring?? would this cause a the double tap???

any advise greatly appreciated....

I, honestly would advise you put a factory trigger in your Glock.

I know some people like the Ghost trigger but I hear enough bad stuff about them that I would much rather have a stock trigger in al of my Glocks.

2nd the factory glock trigger.  Why mess with perfection 

I have my own LLC where I do certain smithing types of work.  I work heavily with Glock pistols and am certified via Glock.  I will however offer some free advice up front.

1 - Due to the lighter trigger pull you could be "bump firing" the weapon.  While not overly common it does happen enough.  If your grip is not secure or if you don't manage recoil or your trigger finger well you may be resetting the trigger under recoil and when the gun settles on the counter recoil phase you may be engaging the trigger again.  It happens quickly. 

2 - Your engagement of the Cruciform and the firing pin ledge can be incorrect or too little.  This can be caused by the connector and or trigger polish job.  A poor polish job, or rather honing can result in altering engagement surfaces and cause issues.

While there are other possible causes, these are the 2 main areas that should be looked at.  In any event I would avoid shooting the weapon until you get it corrected and troubleshoot the shooter and the weapon to determine the issue.  No matter the cause, I would suggest returning the weapon to factory specs and if you wish to have aftermarket work done on the pistol find someone qualified to do the work.  As mentioned I would get it to a certified armorer / gunsmith to take a look at it.